Hey folks -
Back for more

My business is not able to carry a lot of stock on hand except some of the most popular and regularly purchased products. As such most orders that come through are for out of stock "special order" items. These orders often include other product I do have stock of.
Our customers often want to pick up the products that are immediately available right away, and wait for the remainder to come in.
I have found myself having to write comments constantly on the order to separate what has been picked up and what still needs to come in.

I am wondering if there is a way by which I can place a "BO" checkmark, or coloured line or some sort of notation on the order/invoice to denote that a product has been picked up, or vice versa, if a product is backordered and hasn't been picked up by the customer.

Whether on the physical invoice, or just on the internal system. Both would be nice, but I'm not picky.

Any suggestions?